Ministers are proposing a minimum price of 45p a unit for the sale of alcohol in England and Wales as part of a drive to tackle problem drinking.

The Home Office has launched a 10-week consultation on the plan, arguing it will help reduce the levels of ill-health and crime related to alcohol.

It is also considering banning multi-buy promotions, such as two-for-the-price-of-one.

The 45p proposal is 5p higher than the figure suggested by ministers in March.

It comes after pressure has been mounting on the government to follow Scotland's lead, where 50p has been proposed.

The aim of a minimum price would be to alter the cost of heavily-discounted drinks sold in shops and supermarkets. It is not expected to affect the price of drinks in many pubs.

The Home Office said the consultation was targeted at "harmful drinkers and irresponsible shops".

A spokesman added: "Those who enjoy a quiet drink or two have nothing to fear from our proposals."

The 45p minimum would mean a can of strong lager could not be sold for less than £1.56 and a bottle of wine below £4.22.

Research carried out by Sheffield University for the government shows a 45p minimum would reduce the consumption of alcohol by 4.3%, leading to 2,000 fewer deaths and 66,000 hospital admissions after 10 years.

The number of crimes would drop by 24,000 a year as well, researchers suggested.

There has been evidence of some outlets selling alcohol at a loss to encourage customers through the doors, with cans of lager going for 20p and two-litre bottles of cider available for under £2.

'Pre-loading'

Ministers have been particularly critical of such practices, blaming them for what has been dubbed "pre-loading", where people binge-drink before going out.

They have linked this phenomenon to the rising levels of alcohol-related violence and hospital admissions, of which there are more than a million a year.

But the idea of introducing a minimum price - first proposed at 40p in the government's alcohol strategy published in March - has been met with opposition by the industry.

The Scottish government plan, which is not due to start until April 2013, was challenged on legal grounds by the Scotch Whisky Association and the European Spirits Organisation.

What's a unit?

They claimed it was up to Westminster, rather than Holyrood, to decide such an issue and they said it was also incompatible with the EU's "general principles of free trade and undistorted competition".

The legal challenges were heard in the Court of Session in Edinburgh last month and a judgement is expected before the end of the year.

Separately the European Commission is looking into the legality of the Scottish government's actions.

In Northern Ireland, consideration is also being given to minimum pricing, although no final decision has been taken yet.

Andrew Opie, of the British Retail Consortium, said: "Most major retailers believe minimum pricing and controls on promotions are unfair to most customers. They simply penalise the vast majority, who are perfectly responsible drinkers, while doing nothing to reduce irresponsible drinking.

"The government should recognise the role of personal responsibility. It should not allow interfering in the market to regulate prices and promotions to become the default approach for public health policy."

Miles Beale, chief executive of the Wine and Spirit Trade Association, agreed, saying there was "no evidence" minimum alcohol pricing would be effective in tackling alcohol misuse.

The 45p effect

On the face of it, there seems to be little difference between the 45p minimum unit price for alcohol now being proposed and the 40p figure put forward earlier this year.

But in terms of consumption levels - and the subsequent criminal and health costs - the shift is significant.

Research by Sheffield University shows that at 45p consumption drops by 4.3% - a 75% greater effect than would be seen at 40p.

In terms of deaths over a 10-year period, the impact is nearly double. A 45p minimum will save over 2,000 lives compared to under 1,200 for 40p. The effect on crime is also two-fold.

But what the research also shows is that another 5p on the minimum price to bring it to 50p - as Scotland has done - would see a similar increase in impact, which is why campaigners have been pushing for more.

Another area of interest - and possible controversy - is the effect this will have on moderate drinkers.

The research shows a 45p minimum price also affects their buying habits, reducing consumption by 2.3%. That is greater than the reduction likely to be seen in young hazardous drinkers - the so-called binge drinkers.

But health campaigners believe a minimum price is an important step in tackling problem drinking.

Dr Vivienne Nathanson, from the British Medical Association, said the changes in pricing could help to stop young people binge drinking.

She told the BBC: "Alcohol is a dose-related poison, in other words the more you drink the more harm it causes, so by reducing the amount they are drinking over the safe limit you are helping to save them.

"It isn't a small minority of the population who are drinking excessively, it's nearly a quarter. That's a huge number of people who are drinking at levels that are hazardous to their health and we really have to throw everything we can (at it) to save lives."

Eric Appleby, chief executive of Alcohol Concern, said: "We're paying a heavy price for alcohol misuse and setting a minimum unit price will help us on the road to changing this.

"We need tighter controls around licensing, giving local authorities and police forces all the tools they need to get a firm grip on the way alcohol is being sold in their area. We have an opportunity to make an enormous difference to the lives of thousands of people - we must seize it."